I live on the other side of the state. There are two ways that I would suggest that you could winterize the pond. First I would purchase a pond heater, you can purchase one for about $50.00. Second an aerator can be used to prevent freezing, again you can purchase one for about $50.00. In a smaller pond it may be a good idea to use both. The lily should be ok as long as the tuber doesn't freeze.